In the past, humans have experienced a situation wherein their kidneys no longer function to purify their blood because of disease, permanent injury or surgical removal of bo kidneys. Thus, when kidney failure occurs, an accumulation of toxic wastes in the patient's blood results in eventual death from uremic poisoning unless these wastes can be removed by some artificial method or device.
Hemodialysis has been well known as a means for circulating a patient's blood on one side of a membrane which has "minute pores" through which waste products from the blood may pass but which are too small to permit blood cells and protein to be lost. A dialysis fluid generated by e hemodialysis machine is circulated on the opposite side of the membrane to flush and remove these waste products as they are dissipated. As is common practice in hemodialysis treatment, the patient's blood is passed through the dialyzer for various periods of time up to six hours with this type of treatment repeated several times each week. Various critical problems occur in the use of this type of treatment in that the dialyzer and the hemodialysis machine must be cleaned and disinfected after each use to prevent contamination and complications to the patient.
With the old type dialyzers and hemodialysis machines, it was necessary to manually clean and flush the dialyzer and associated tubing with a subsequent sterilization process following. Since this required the use of trained technicians to perform this service, in most cases the treatment could take place only at hospitals or dialysis treatment centers, with very little of this treatment performed at the patient's home.
In the early 1970's, a major step was taken in that the dialyzer was improved and perfected in a disposable form that was considerably cheaper than the previous dialyzers used. Even in this new disposable form, the dialyzer costs average between $25 and $35. Because these dialyzers are intended to be disposable, they eliminate the problems connected with the cleaning and sterilizing of the dialyzer before subsequent use. However, because of the relatively high cost of the disposable dialyzer and, in addition, the cost of the blood tube set that is required to be used with the dialyzer, the expense of the individual treatments to the patient is still quite high primarily because of the required continuing treatment.
With the continued use of the disposable dialyzers, an attempt was made to develop a procedure for reusing the dialyzer more than once in order to effect a much more economical treatment schedule for the patient.
In the prior art various attempts have been made to develop suitable reuse machines which could be utilized in conjunction with the hemodialysis machines to automatically clean, flush and disinfect the disposable dialyzer and blood lines and the hemodialysis machine. With the development of these devices, it became more feasible for the individual patients to treat themselves in the privacy of their own homes. In this way, the costs are considerably reduced, not only because the equipment can be reused but also due to the fact that highly skilled technicians are no longer required with their attendant costs.
These prior art reuse devices have suffered on many occasions from various shortcomings such as leakage at various fittings, corrosion of metal parts used within the system, inability to be used with more than one type of artificial kidney or dialyzer, and the inability to adjust the cleaning and disinfecting cycles to fit various time needs. Thus, these shortcomings produced major problems in that there was always a risk of contamination with the inability to properly test the dialyzer and system so that only competent dialyzers and blood tubing sets would ever be reused.
In addition to the above background discussion, it is interesting to note that various research studies have been performed to determine if there is a difference in patient mortality related to the multiple use of dialyzers as compared to single use. As a result of this research, it has been found that there are significant benefits obtainable by the multiple use of the dialyzer. It was shown as a matter of course that two primary patient symptoms, namely, back pain and chest pain, were markedly reduced with the use of reprocessed dialyzers. In addition, the reused dialyzers also showed a far superior bio-compatibility to that of the new dialyzers.
Within recent time the medical profession has begun to standardize procedures for reuse of dialyzers. In establishing these standards, four major problem areas have been identified. These areas are: (1) membrane transfer efficiency, (2) mechanical competency of the dialyzer and blood lines, (3) chemical contamination and (4) bacteriological safety. The characteristic of the dialyzer which is of utmost importance is its ability to transfer dissolved solutes. One test which is provided to determine the effectiveness of the dialyzer to transfer solutes is the "clearance" test. This test verifies the mass transfer efficiency and the mechanical integrity of the dialyzer and therefore covers the first two major problem areas which are of concern.
An additional problem that has confronted many users of hemodialysis machines and reuse has been the exposure to chemicals used in the cleaning and disinfecting process. The chemicals currently being used to recondition dialyzers include hypochlorites, iodoforms, hydrogen peroxide, peracetic acid, formaldehyde, glutaraldehyde and various combinations of these groups. Because of their high concentrations, these chemicals can pose potential health problems. The use of these chemicals indiscriminately have made it difficult for an individual person to manually reuse and clean the dialyzers, thus setting up the necessity for automatic reuse devices. As a result of these problems, it has been recognized that it is important to provide a closed system to eliminate any fumes and the exposure of the user or patient to these chemicals during the reuse process.
The last area of concern requires that the dialyzer, blood tubing set and hemodialysis machine be properly disinfected and allowed to remain in a sealed condition during storage and prior to the next dialysis treatment. This has been a characteristic problem of many of the older prior art reuse devices in that tubing, dialyzer and equipment connections must be broken and made with the integrity of the overall system violated with the possibility of chemical, air or bacteria contamination being introduced.
As a response to these four major concerns, the present invention was developed as a means for vastly improving the reuse cycle for the dialyzer and blood tubing sets in order to improve and correct the various deficiencies which have been noted in the prior art devices and systems.